Ridley Scott stated in the DVD commentary for
Alien (and the accompanying 2001 DVD documentary
Alien Evolution) that the concept behind the origin of the
xenomorphs is that nothing so deadly could have evolved naturally, but was instead designed through genetic engineering by some other ancient race as a
biological weapon. He described the crashed Derelict encountered by the
Nostromo as essentially a "bomber" that would carry payloads of
xenomorph eggs and drop them onto targeted planets. This concept was present since work on the first film, though Scott went on to refine and expand on it over thirty years later in the prequel
Prometheus - which established that not only were the
xenomorphs created by the "Engineers" (the race of the "Space Jockey" the
Nostromo crew found), but specifically formed using a hostile mutagenic pathogen (the "black goo" termed "Chemical A0-3959X.91"). The second core concept was that in order to keep the monster horrifying and unpredictable, it would metamorphosize through several radically different life stages - one of which involved a larval stage gestating inside of a human host before fatally bursting out. Another concept present since Scott's production on the original film is that
xenomorphs have flexible genetic material which is designed to adapt to whatever environment they are in, by incorporating some genetic information from their host that is native to that environment. The
xenomorph on the
Nostromo has a bipedal humanoid stature because its larval form gestated inside of a human, resulting in what Scott described as "the man-version of Alien". Subsequent spinoffs demonstrated variations on this concept: a
xenomorph gestated inside of a quadruped like a dog or ox results in a quadrupedal, panther-like
xenomorph (
Alien 3), and one gestated inside of a Predator/Yautja will become a powerfully built "Predalien" with mandibles (
Alien vs. Predator).
Appearance --> When standing upright, the Aliens are bipedal in form, though, depending on their host species, they will adopt either a hunched stance or remain fully erect when walking, sprinting, or in hotter environments. Their overall stance and general behavior seem to result from the mixture of the respective DNA of the embryo and its host. They have a skeletal,
biomechanical appearance and are usually colored in muted shades of black, gray, blue or bronze. Their body heat matches the
ambient temperature of the environment in which they are found, so they do not radiate heat, making them indistinguishable from their surroundings through
thermal imaging. but from
Aliens onwards the blade design increased in size and changed in appearance to more closely resemble a slashing weapon. From
Alien Resurrection onwards, the tails have a flat ridge of spines at the base of the blade. This was introduced to help them swim convincingly, and was left intact in the subsequent crossovers. The original shooting script for
Aliens and the novelization both featured a scene in which Lieutenant Gorman is "stung" by the barb tail and rendered unconscious; in the final cut of the movie, Gorman is knocked out by falling crates. As a weapon, the strength of the tail is very effective, having been shown to be strong enough to impale and lift a
Predator with seemingly little effort. The aliens have elongated, cylindrical
skulls. In the novelization of
Alien, the character Ash speculates that the xenomorphs "see" by way of electrical impulse, similar to some fish's
Ampullae of Lorenzini. This method is illustrated in the original
Aliens Versus Predator PC game and reused for the
Predalien 8 years later. The Alien's
inner set of jaws on its tongue is powerful enough to smash through bone and metal. and abandoned in
Aliens vs. Predator: Requiem in favor of the ribbed design. Throughout their appearances, human-spawned Aliens have been shown to have different numbers of fingers. In
Alien, the creature has
webbed, six-fingered hands. In
Aliens, the number of fingers is reduced to three, with two "paired" and a single, opposable thumb. The fingers are also shown to be much longer and more skeletal. In
Alien Resurrection, the number of digits is increased to four, with two long middle fingers and a pair of thumbs. This design is kept in the
Alien vs. Predator films, though the hands were made bulkier in order to make the Aliens seem more formidable against the Predators. Aliens have been alternatively portrayed as both
plantigrade and
digitigrade organisms, usually relative to their hosts. Human-spawned Aliens were usually portrayed as having humanoid hind limbs, while in
Alien 3 the featured Alien sported double-jointed legs due to its quadrupedal host. This characteristic would be continued in
Alien Resurrection for the human-spawned Aliens. Tom Woodruff, who had previously played the "dog-alien" in
Alien 3, described the human-spawned Aliens in
Resurrection as feeling more like a dog than the previous creature, despite having been born from human hosts. The human-spawned Alien warriors would revert to a plantigrade posture in
Alien vs. Predator.
Physiology Alien blood contains concentrated
hydrofluoric acid and
sulfuric acid and is capable of corroding almost any substance on contact with alarming speed. It is dull yellow in color and appears to be pressurized inside the body so that it spurts out with great force when the creature is wounded.
Ron Cobb suggested the idea of the Alien having acidic blood as a plausible means to make the creature "unkillable"; if one were to use traditional firearms or explosives to attack it, its blood would eat through the hull of the ship. The
Alien novelization suggests that, at least at the "facehugger" stage, the acid is not blood but a fluid maintained under pressure between a double layer of skin. In the
Aliens vs. Predator: Requiem documentary "Science of the Alien", it is hypothesized that the Aliens' acid blood could contain
sulfuric acid due to its corrosiveness and the conspicuously toxic effects on living human tissue. The documentary also speculates that Aliens are immune to their own acidic and toxic liquids due to an endobiological build-up, similar to the human stomach's ability to protect itself from its own digestive fluids. The documentary takes this hypothesis one step further and speculates that the Alien organism's protection system against its own acidic blood is a bio-organically produced
Teflon-like insulation. In the original
Alien, the facehugger is shown to be able to "spit" acid, dissolving the faceplate of Kane's helmet and allowing the creature immediate access inside. This ability is also exhibited by adult Aliens in
Alien 3 and
Alien Resurrection; much like a
spitting cobra, they use it to blind their victims. Aliens can produce a thick, strong
resin that they use to build their hives and to
cocoon their victims, and they can use the walls of their hives as
camouflage. Aliens also salivate heavily in the form of a sticky, clear slime; while not a toxic substance in and of itself, it is common for the
Alien films to use it as a suspense-building device, wherein a character will notice the falling saliva before noticing its source lying in wait above them. Their body structure also differs, having two pairs of arms, one large and one small. The queen's head is larger than those of other adult Aliens and is protected by a large, flat crest, like a crown, which varies from queen to queen. Unlike other aliens, the queen's external mouth is separately segmented from the rest of her head, allowing her to turn her mouth left and right almost to the point where it is facing perpendicular to the direction of the rest of her head. In the second film,
Aliens, unlike other adults and queens, the queen had high-heel protrusions from her feet. Her skin is very strong compared to other xenomorphs. Egg-laying Alien queens possess an immense
ovipositor attached to their lower torso, similar to a queen termite's. Like
some insect
queens, there appears to be no need for an Alien queen's eggs to be fertilized. that consists of a lattice of struts resembling massive insect legs. In the original cut of
Alien, the Alien possessed a complete lifecycle, with the still-living bodies of its victims converted into eggs. However, a scene showing crew members Brett and Dallas being converted into cocoons was cut for reasons of pacing, leaving the ultimate origin of the eggs obscure. This allowed
Aliens director
James Cameron to introduce a concept he had initially conceived for a spec script called
Mother, a massive mother Alien queen which laid eggs and formed the basis for the Aliens' life cycle. Cameron conceived the queen as a monstrous analogue to Ripley's own maternal role in the film. The queen was designed by Cameron in collaboration with special effects artist
Stan Winston, based upon an initial painting Cameron had done at the start of the project. The Winston Studio created a test foamcore queen before constructing the full hydraulic
puppet which was used for most of the scenes involving the large Alien. Two people were inside working the twin sets of arms, and puppeteers off-screen worked its jaws and head. Although at the end of the film, the queen was presented full-body fighting the power-loader, the audience never sees the legs of the queen, save those of the small-scale puppet that appears only briefly. In
Aliens, Cameron used very selective camera-angles on the queen, using the '
less is more' style of photography. Subsequently, the movie won an
Oscar for Visual Effects. An adult queen was to reappear in
Alien Resurrection. The original mechanical head previously used in
Aliens was provided by
Bob Burns and was an altered design. It was repainted with a blend of green and brown, giving it a shimmering, insect-like quality. This color concept would be abandoned in
Alien vs. Predator in favour of the original black color scheme. This is explained by the Brothers Strause as a means of quickly building an army of Aliens before the young queen evolves into its sedentary, egg-laying state.
Egg Adult xenomorphs are capable of creating their own reproductive egg ("ovamorph") by
embedding their prey into an organic substance that (in theory) metabolically reacts to merge host-parasite
genetic material. The entire process is xeno-dominant, resulting in a facehugger. The eggs laid by the queen are ellipsoidal, leathery objects between one-half and one meter (two and three feet) high with a four-lobed opening at the top. The eggs can remain in a stasis mode for years, possibly indefinitely, until nearby movement is detected. As a potential host approaches, the egg's lobes unfold like flower petals, and the parasitic facehugger extracts itself from the egg and attaches itself to the potential host. Giger initially designed the eggs with a much more obvious vaginal appearance, complete with an "inner and outer vulva". The producers complained that Catholic countries would ban the film if the allusion was too strong, so Giger doubled the lobes to four so that, in his words, "seen from above, they would form the cross that people in Catholic countries are so fond of looking at". The host is kept alive via the facehugger supplying oxygen. This is an alternate explanation to
horizontal gene transfer as to how the resulting xenomorph is able to adopt the characteristics of its host. Giger's original design for the facehugger was a much larger creature with eyes and a spring-loaded tail. Later, in response to comments from the filmmakers, Giger reduced the creature's size substantially. At first, Giger assumed that the facehugger would wrap around the outside of the astronaut's helmet, but Scott decided that it would have far more impact if the facehugger was revealed once the helmet was removed. Scott and Giger realized that the facehugger should burn through the helmet's faceplate with its acid blood; subsequent redesigns of the space helmet included a far larger faceplate to allow for this.
Dan O'Bannon initially conceived the facehugger as somewhat resembling an octopus, possessing tentacles. However, when he received
H. R. Giger's designs, which substituted finger-like digits for tentacles, he found Giger's design concept to be superior. Since no one was available at the time, O'Bannon decided to design the facehugger prop himself. The technical elements of the musculature and bone were added by
Ron Cobb. Giger's initial design for the smaller facehugger had the fingers facing forward, but O'Bannon's redesign shifted the legs to the side. When the
foam rubber sculpture of the facehugger was produced, O'Bannon asked that it should remain unpainted, believing the rubber, which resembled human skin, was more plausible. There has been some debate about the sexual appearance of the facehugger, some saying it unmistakably resembles female genitalia. In
Aliens, the facehuggers were redesigned by
Stan Winston so that they would be capable of movement. Unlike the creatures in the first film, the creatures would take a much more active role in impregnating their victims. When Ripley throws one off her, the facehugger is now capable of scuttling across the floor and leaping at its prey, wrapping its tail around the victim's throat. The facehugger is also shown to be capable of independently surviving outside of its egg. Due to the film's budget, only two fully working facehuggers were built. In
Alien 3, another addition was planned but ultimately dropped, a "super-facehugger" that would carry the embryo of the queen Alien. This super-facehugger is briefly glimpsed in the Assembly cut of
Alien 3 but not identified as such. It made a brief appearance in the canonical
Alien book called
Alien: Sea of Sorrows, set after the events of
Alien Resurrection, about the grandson of Ripley Clone 8, Ellen Ripley's clone.
Chestburster --> --> After impregnation, facehuggers die and the embryo's host wakes up afterward, showing no considerable outward negative symptoms and a degree of
amnesia regarding events at the time of implantation. Symptoms build acutely after detachment of the facehugger, the most common being sore throat, slight
nausea, increased congestion, and moderate to extreme hunger. and other structural changes that enable adaptation to its new environment. According to Weyland-Yutani medical scientists in
Aliens: Colonial Marines, the chestburster will draw nutrients from the host's body in order to develop a placenta as it grows, attaching itself to several major organs in the process. The placenta has cancerous qualities, such that even if the embryo were removed surgically, the placenta would simply cause the affected organs to shut down, resulting in death; the only exceptions to this are from human-xenomorph hybrid hosts like the cloned Ripley 8, who survived an extraction procedure without issue. Over the course of one to twenty-four hours--indeterminable in some cases, and sometimes up to a week, in the case of some queens--the embryo develops into a chestburster, at which point it emerges, violently and fatally ripping open the chest of the host. There is no on-screen explanation of the reasons for the different incubation times. Fully-grown aliens may avoid harming species acting as hosts for un-emerged chestbursters, though this may only be in the case of a queen embryo, as depicted in
Alien 3. When a chestburster erupts from the body of a human host, it is less than tall, although the embryo can vary in size from a guinea pig to a large dog depending on the size and species of the host. Its appearance and adaptive characteristics are also determined by the host. Typically, its first instinct upon emerging is to flee and hide until full maturation, as well as find a source of nutrition. However, it soon undergoes a dramatic growth spurt, reaching adult size in a matter of hours; in
Alien, the chestburster had grown to in height by the time the
Nostromo crew located it again. The chestburster is shown to have molted before reaching maturity. Giger had produced a model of a chestburster that resembled a "degenerate plucked turkey" and was far too large to fit inside a ribcage. Much to Giger's dismay, his model reduced the production team to fits of laughter on sight. Scott drafted a series of alternative designs for the chestburster based on the philosophy of working "back [from the adult] to the child" and ultimately produced "something phallic". The chestburster in the original
Alien was armless, but arms were added in
Aliens to facilitate the creature crawling its way out of its host's corpse. This concept would be abandoned in
Alien Resurrection, but it would return in
Alien: Covenant.
Cocoon The xenomorph lifecycle is expanded in the movie
Alien: Romulus with the introduction of a "cocoon" stage, which bridges the gap between the chestburster and the fully-grown adult xenomorph stages as witnessed by the characters Bjorn and Kay while aboard the derelict
Renaissance space station. It is shown that a chestburster which had emerged from their crew-mate Navarro had attached itself to a wall and electrical cables building a biomechanical protective cocoon around itself after shedding its skin. While inside the cocoon, the chestburster
transformed into a fully-grown adult drone xenomorph.
Alternative forms Aliens take on various forms
depending on the characteristics of their hosts. Most of the Aliens seen to date have been human-spawned, but a number of Aliens born from other hosts have also been seen. Some of these are also a different variants or species altogether such as the Neomorph and Deacon.
"Dragon" The "Dog Alien" or "Ox Alien", (also known as "Runner Alien" in the expanded universe stories) and referred to in-film as "Dragon", was introduced in
Alien 3. The creature itself shares the same basic physical configuration and instincts as the other Aliens shown in the previous films, although there are several differences due to the host from which it was spawned (a
dog in the theatrical cut, or as an
ox in the novelized version and the assembly cut). The dog Alien in its chestburster form is a miniature version of the adult, unlike the larval human- and Predator-spawned chestbursters. The adult is primarily
quadrupedal, has
digitigrade hind legs, and lacks the dorsal tubes of the human-spawned variety. The only differences behavior-wise was that this Alien behaved more like a dog or another quadrupedal animal that generally is prone to using its mouth instead of its front legs as its primary weapon to attack and maul its victims with its teeth. This Alien, even when actively provoked, would not attack or kill Ripley, due to the queen growing inside her. This, however, changed towards the movie's climax, at which point the monster, after surviving a torrent of molten lead, burst from the liquid and went into a rampage, pursuing Ripley and presumably attempting to kill her until she destroyed it by showering it with freezing water, causing it to explode from
thermal shock. Originally, H. R. Giger was approached on July 28, 1990, by
David Fincher and
Tim Zinnemann, and was asked to redesign his own creations for
Alien 3. Giger's new designs included an aquatic face-hugger and a four-legged version of the adult Alien. As Giger said in an interview, "I had special ideas to make it more interesting. I designed a new creature, which was much more elegant and beastly, compared to my original. It was a four-legged Alien, more like a lethal
feline—a
panther or something. It had a kind of skin that was built up from other creatures—much like a
symbiosis." However, when Tom Woodruff and Alec Gillis of
Amalgamated Dynamics told Giger that they had their own design, Giger expressed himself as "very upset" and that the creature he had especially designed was his "baby". Even after the production severed contact, Giger continued to fax suggestions to Fincher and made full-scale drawings and a sculpt of the Alien, all of which were rejected. Giger would later be angered by the end credits of the released film presenting him as merely the creator of the original creature, and the fact that
Amalgamated Dynamics personnel gave a series of interviews that minimized Giger's contribution. Fox eventually reimbursed Giger, but only after he refused to be interviewed for their behind-the-scenes documentary of
Alien 3. However, Giger would comment that he thought the resulting film was "okay" and that the Alien was "better than in the second film".
Newborn '' In
Alien Resurrection, due to significant genetic tampering in an attempt to recover DNA from the deceased Ellen Ripley and the Alien queen within her, the resulting cloned Aliens show a number of minor human traits. The cloned queen inherits a perversion of a human womb, and as a result, it ceases to lay eggs and gives birth to a
humanoid mutant hybrid. Physically, the human/Alien Newborn is very different from other alien young, being larger, with pale, translucent skin, a
skull-shaped face with eyes, a human tongue, and a complete absence of a tail. The Newborn fails to bond with its Alien queen mother, killing it, and imprinting on the Ripley clone instead. The Newborn creature was originally scripted by
Joss Whedon as being an eyeless, ivory-white quadruped with red veins running along the sides of its head. It had an inner jaw, with the addition of a pair of pincers on the sides of its head. These pincers would have been used to immobilize its prey as it drained it of blood through the inner jaw. The creature was originally going to rival the queen in size, but
Jean-Pierre Jeunet asked ADI to make the human/Alien
hybrid, known as the Newborn, more human than Alien. The Newborn's eyes and nose were added to improve its expressions to make it a character, rather than just a "killing machine", and give it depth as a human-like creature.
Predalien This variation is the result of a facehugger impregnating a
Predator. The "Predalien" was first depicted in a painting by
Dave Dorman, and subsequently featured in the
Aliens versus Predator comics and games. A Predalien chestburster debuted in the final scene of
Alien vs. Predator (2004), but did not make a full on film appearance as an adult until
Aliens vs. Predator: Requiem (2007). The Predalien shares many characteristics with its hosts, such as long hair-like appendages,
mandibles, skin color, blood that glows in the dark (though still acidic), and similar vocalizations. It is a large, bulky creature, and possesses physical strength greater than that of human-spawned Aliens. Like human-born Aliens, it is also shown to be stronger than its host species, as evidenced by its ability to pin, push, and knock a Predator away with ease.
Deacon The dark-blue Deacon is a different species that makes an appearance in
Prometheus, though it clearly shares traits similar to the xenomorph, including a similar life-cycle. The Deacon is the result of a "Trilobite" (which takes its name from
a group of extinct marine arthropods), a large facehugger-like creature, attacking and impregnating an Engineer. After some time spent gestating, it will burst out of its host, with the notable difference that it is "born" almost fully developed. The Deacon's emergence drew inspiration from the birth of
foals, with the iridescent appearance for its skin being based on the equine placenta, and the protruding jaw inspired by the
goblin shark. Its fate is unknown, though the tie-in comic book
Prometheus: Fire and Stone, also set on LV-223, features a mutated mountain with acidic veins which are implied to be the heavily mutated Deacon's deadly back spines.
Neomorph The pale-white Neomorph features in
Alien: Covenant. == Critical response ==